1. Field of the Invention
The present invention is directed to a method for controlling a valve which injects fuel into a combustion chamber of an internal combustion engine.
2. Description of the Related Art
A known valve for injecting fuel into the combustion chamber of an internal combustion engine (DE 10 2011 006 202 A1) has a valve housing which is provided with a fuel inlet and a valve opening which is connected to the fuel inlet. The valve opening is implemented in a hollow valve-seat carrier, which closes the valve housing on the combustion chamber side, and is enclosed by a valve seat. A valve member which is displaceable axially in the valve-seat carrier closes the valve opening under the effect of a valve-closure spring acting on it. For the purpose of a defined release of the valve opening, a piezoelectric actuator drives the valve member to carry out strokes against the restoring force of the valve-closure spring. For metering the fuel quantity injected with each stroke into the combustion chamber through the valve opening, the valve is controlled in such a way that electrical control signals, which determine the stroke size of the strokes of the valve member, are applied to the actuator. The control signals may be a time-limited voltage or a charge. The control signals are usually generated in an engine control unit as a function of the instantaneous operating data of the internal combustion engine.
As a consequence of wear at the valve seat and the valve-closure member, as well as of changes in the stroke of the actuator during the service life of the valve, the stroke of the valve member and thus the metering of the fuel injected into the combustion chamber are reduced if the control signal remains unchanged.